Machine for blast cleaning with grit such articles as castings



E. F. FISHER MACHINE FOR BLAST CLEANING WITH GRIT SUCH ARTICLES ASCASTINGS Filed June 12, 1946 June 22,-1948.

IN V EN TOR.

Patented June 22, 1948 OFFICE MACHINE FOR BLAST CLEANING WITH GRIT SUCHARTICLES AS CASTIN GS Ernest F. Fisher, Meredith, N. H.

Application June 12, 1946, Serial No. 676,271

moving scale and moulding sand.

According to this invention a stream of sand or metallic shot or gritmerges with a high velocity air stream and attains the same velocity asthe air stream. This high velocity mixture of air and gritty particlesis directed against the surfaces of the castings and loosens the sandand scale therefrom. The spent particles of grit are collected and putback in the air stream for re-use, while the fine dust arising from theoperation and the spent air are exhausted from the apparatus andconducted to a dust collector.

The invention will be further described in connection with theaccompanying drawings in which Figure 1 is a vertical cross sectiontaken on line I -l of Figure 2. Figure 2 is a. horizontal cross sectiontaken on line 22 of Figure 1. Figure 3 is a, vertical section showingblower l 2 which supplies the high velocity air for projecting thestream of grit that flows through tube 6 into the orifice of nozzle [6.Figure 4 is a vertical section of another form of blower. 3

Referring now to these drawings, the apparatus of Figures 1 to 3comprises an enclosure or casing I which, with hinged hopper 2 forms areason ably air tight enclosure for the castingsto be cleaned. Withinthis enclosure is ram 3 which is designed to be raised and lowered in areciprocating fashion by means of the revolving pinions 4 and thecooperating racks 5 which are attached to ram 3. This reciprocatingvertical motion of the ram is affected by suitable reversing and limitswitches controlling a motor (not shown) for driving shaft 4a.

Ram 3 is guided in casing I by liners I which afford clearances betweenthe ram and the walls of the enclosure for the spent grit to drop downinto conveyor trough 8. This spent grit is conveyed by the spiralconveyor 9 into elevator I l) which elevates the grit so that it willflow into separator I 041 to be cleaned. The refuse is dischargedthrough spout II and the cleaned grit flows by gravity through flexibletube 6a and connecting tube 6 into nozzle l6 of blower [2.

The hopper 2 which is hinged to the main casing I at point H servesseveral purposes. It serves as a door for casing I. It serves as aspillway for the castings as they roll oif the inclined top of ram 3. Itserves to convey the 6 Claims. (Cl. 51-44) castings from the floor tothe upper part of casing I or mother words, to load the machine. Thehopper 2 is raised and lowered by the winch H.

In operation, castings are placed in hopper 2 whenit is in a loweredposition as shown in dotted lines. It is then raised by the winch I7 andlatched in position and the castings discharge into casing I dropping onram 3 in its lowermost position as shown. The ram 3 isstarted'reciprocating slowly up and down while the blower I2 dischargesthe air stream mixed with grit onto the castings as they rise upward andspill on the inclined top of ram 3 into hopper 2. As the ram descendsthe castings roll ofi hopper 2 back onto ram 3. This repeated up anddown motion of the ram turn the castings over and over thus presentingall surfaces of the castings to the blast of air and grit.

The spent grit drops down through the clearances betweenram 3 and. thewalls of casing l into trough 8 Where. the grit is conveyed by spiralconveyor 9 to the elevator H] which elevates the. grit to separator Illawhere it is cleaned, the refuse passing out through spout II and thecleaned grit flows by gravity down tube 6 into the orifice of nozzle 16of blower l2. The dust laden air is exhausted from casing I throughopening I8 which connects with an exhaust fan which maintains a slightnegative pressure within the apparatus to prevent dust from dissipatinginto the room.

After the castings are cleaned the ram 3is raised to its topmostposition or limit of travel upward and the castings spilled into hopper2 which is then lowered to the floor by winch l1, thus completing theoperation of cleaning.

The method of propelling the grit is shown in Figure 3. The grit is fedthrough tube 6 to the orifice of the blower discharge nozzle [6 and doesnot come in contact with any part of the blower housing or impeller.Thus there is no erosion of the parts. Sufficient velocity is impartedto the air by the impeller [9 to give the grit a velocity ofapproximately28,000 feet per minute which is suificient to produce agood job of cleaning.

Any type of pressure blower can be used for supplying the necessary airfor propelling the grit. The nozzle It; can be swung back and forthabout the axis 20 through an arc suflicient to cover any blast area incasing I so that all castings are reached by the blast. This nozzle canbe separate and distinct from the blower as in Figure 4. The blower inFigure 4 discharges the air into nozzle is which swings through an areing hopper attached to said casing and also adapted to form a closurefor said opening, means to raise and lower said hopper, a verticallyreciprocating ram for tumbling said material within said casing, the topof said ram being inclined downwardly toward said hopper, means todirect a high velocity stream of air and grit against said material tobe cleaned, and means to reciprocate said ram.

2. A blast cleaning machine comprising, in combination, a verticalcasing to contain material to be cleaned, the upper portion of saidcasing having an inwardly sloping side provided with an opening therein,a loading and unloading hopper attached to said casing and also adaptedto form a closure for said opening, a

vertically reciprocating ram for tumbling saidmaterial within saidcasing, the top of said ram being downwardly inclined toward saidhopper, means to reciprocate said ram, the upper limit of movement ofthe top of said ram being above the lower edgeo'f-fsaid opening, mean todirect a high velocity stream of air and grit against said material tobe cleaned, and means to raise and lower said hopper.

3. A blast cleaning machine comprising, in combination, a verticalcasing to contain material to be cleaned, the upper portion of saidoasing having an inwardly sloping side provided with an opening therein,a loading and unloading hopper attached to said casing and also adaptedto form a closure for said opening, a vertically reciprocating ram fortumbling said material within said casing, the top of said ram beingdownwardly inclined toward said hopper, means to reciprocate said ram,the upper limit of movement of the top of said ram being abovethe loweredge of said opening, the lower limit of movement of .saidram beingbelow the lower edge ofsaid opening, means to direct a high velocitystream of air and grit against said ma- 4 terial to be cleaned, andmeans to raise and lower said hopper. I

4. A blast cleaning machine comprising, in combination, a verticalcasing to contain material to be cleaned,.the upper portion of saidcasing having an inwardly sloping side provided with an opening therein,a loading and unloading hopper attached to said casing and also adaptedto form a closure 'for said opening, means to raise and lower saidhopper, a vertically reciprocating ram for tumbling said material withinsaid casing, the top of said ram being inclined downwardlyjtoward saidhopper, nozzle means swingable back and forth for directing a highvelocity stream of air and grit against said material to :be cleaned,and means to reciprocate said ram.

5.A' blast cleaning machine comprising, in

combination, a vertical casing to contain material to be cleaned, theupper portion of said casing having an inwardly sloping side providedwith an opening therein, a loading and unloading hopper attached to saidcasing and also adapted to form a closure for said opening, a verticallyreciprocating ram fortumbling said material within, said casing, the topof said ram being downwardly inclined toward said hopper, means toreciprocate said ram, the upper limit .of movement of the topof said rambeing above the lower edge of said opening, nozzle means swingable backand forth for directing a high velocity stream of air and grit againstsaid material to be cleaned, and means to raise and lower said hopper.

6. A blast cleaning machine comprising, in combination, a verticalcasing to contain material tobe cleaned, the upper portion of saidcasing having an inwardly sloping side provided with an opening therein,a loading and unloading hopper attached to said casing and also adaptedto form a closure for said opening, a vertically reciprocating ram fortumbling said material within said casing, the top' of said ram beingdownwardly inclined toward said hopper, means to reciprocate said ram,the upper limit of movement of the top of said ram being above the loweredge of said opening, the lower limit of movement of said ram beingbelow the lower edge of said opening, nozzle means swingable back "andforth for directing a high velocity stream of'air and grit against saidmaterial to be cleaned, and means to raise and lower said hopper.

ERNEST F. FISHER.

